Abstract: A nozzle system for use in a flow cytometer for analyzing particles in a fluid stream and a method of orienting particles in a flow cytometer. The nozzle system may include a nozzle having a longitudinal axis, an interior surface defining a fluid flow path for orienting particles in the nozzle, and a downstream orifice through which a fluid stream exits. The nozzle system may also include a conduit positioned to introduce a core stream containing particles at a location offset from the longitudinal axis and a baffle downstream of the conduit to deflect the fluid stream. The method may include the steps of causing a sheath fluid to flow through the nozzle, introducing a core fluid stream into the sheath fluid at a location offset to the longitudinal axis of the nozzle, and deflecting the core fluid stream with a baffle.

Abstract: A disposable blood analysis cartridge may include a sample collection reservoir, an absorbance measurement channel, and an optical light scattering measurement channel. One or more valves may be disposed between the sample collection reservoir and the absorbance measurement channel and/or the optical light scattering measurement channel. A negative pressure may be applied to the cartridge to pull sample from the sample collection reservoir through the one or more valves and into the absorbance measurement channel and/or the optical light scattering measurement channel. Once the sample is pulled into the absorbance measurement channel and/or the optical light scattering measurement channel, the one or more valves may be closed. With the one or more valves closed, and in some cases, a pusher fluid may be provided to push the fluid sample to other regions of the disposable fluid blood analysis cartridge.

Abstract: Each of a first measurement unit and a second measurement unit (sample analyzer) includes: a reagent storage section in which a plurality of holder parts are arranged side by side, each of the holder parts including a setting part in which a reagent container having an RFID tag attached thereto is set, and an antenna part which transmits/receives a radio wave to/from the RFID tag of the reagent container set in the setting part; and a left face part and a right face part which block a radio wave communication path between the antenna part of one of the holder parts and the RFID tag of the reagent container set in another one, of the holder parts, adjacent to the one of the holder parts.

Abstract: A method for analyzing blood cells in a whole blood sample obtained from a cat is provided. An electrical measurement result and an optical measurement result of the whole blood sample are acquired. The electrical measurement result is obtainable by electrically measuring blood cells in the whole blood sample and the optical measurement result is obtainable by optically measuring blood cells in the whole blood sample. On the basis of the electrical measurement result and the optical measurement result, volume of red blood cells in the whole blood sample is calculated.

Abstract: Fluid analyte sensors include a photoelectrocatalytic element that is configured to be exposed to the fluid, if present, and to respond to photoelectrocatalysis of at least one analyte in the fluid that occurs in response to impingement of optical radiation upon the photoelectrocatalytic element. A semiconductor light emitting source is also provided that is configured to impinge the optical radiation upon the photoelectrocatalytic element. Related solid state devices and sensing methods are also described.

Abstract: A blood glucose meter includes a front attachment part to which a test piece is attached, a measurement part for measuring a component of blood collected via a blood guide passage in the test piece, and a monitor for displaying the measurement results obtained by the measurement part. When the device is placed on a horizontal plane by referring to the display face of the monitor as the upper side and the opposite side as the lower side and placing the display face of the monitor upward, the central axis of the test piece extends obliquely downward toward the front side. The blood glucose meter comprises a main part provided with the monitor and a linking part between the main part and the front attachment part. The top face of the linking part is placed roughly parallel to the central axis line and is provided with an ejector lever.

Abstract: A microfluidic-based flow assay and methods of manufacturing the same are provided. Specifically, the microfluidic flow assay includes a substrate surface comprising lipid coated particles and microfluidic channels through which a blood product can flow. The lipid coated particles comprise functional molecules that can induce or inhibit the coagulation cascade.

Abstract: Provided is a blood separating agent that can form an excellent partition wall in an intermediate layer between clot and serum or between blood cell components and plasma even under low-temperature centrifugation conditions, is less likely to form crevices in the partition wall, is less likely to have any effect on test values, and offers stable performance even after long-term storage. The blood separating agent contains: a polymer for the blood separating agent which is composed of a (meth)acrylic acid ester-based polymer and has a viscosity of 10 to 200 Pa·s at 25° C. and a ratio of viscosity at 15° C. to viscosity at 25° C. of below 4.6; an inorganic powder; and a polyalkylene glycol having a number average molecular weight of 700 or more, wherein the polyalkylene glycol is mixed at a concentration of 5% by weight or less of the total weight of the blood separating agent.

Abstract: A method for classifying particles according to one or more particle characteristics. The method includes operating multiple flow cytometer units to form separate fluid streams that each contain a mixture of particles and to classify particles in the mixtures by interrogating the streams with beams of electromagnetic radiation. A common processor receives and processes information from the units and sends a control signal in real time to adjust the unit's operation as a function of the information received by the common processor.

Abstract: The present invention, provides a flow cytometry apparatus for the detection of particles from a plurality of samples comprising: means for moving a plurality of samples comprising particles from a plurality of respective source wells into a fluid flow stream; means for introducing a separation gas between each of the plurality of samples in the fluid flow stream; and means for selectively analyzing each of the plurality of samples for the particles. The present invention also provides a flow cytometry method employing such an apparatus.

Abstract: Detection of detection target substances at a sensor portion is expedited and the efficiency thereof is improved in biological substance analysis, to enable accelerated analysis with high sensitivity. A biological substance analyzing cell equipped with a reaction chamber having a sample supply space, an acoustic matching layer which is provided at a predetermined region of an inner wall of the reaction chamber that faces another inner wall, and a sensor portion provided within the reaction chamber is employed. Ultrasonic waves are emitted such that a standing wave are generated between the acoustic matching layer and the inner wall of the reaction chamber that faces the acoustic matching layer. The detection target substance is concentrated by the capturing forces of the standing waves, and the concentrated detection target substance is detected at the sensor portion.

Abstract: Methods and devices for analyzing fluid variables. The devices analyze fluid variables by measuring cessation of fluid flow through the medium or a change in flow rate due to an inherent property of the fluid variable, or due to a modification of the fluid variable as the fluid migrates through the medium; or by measuring relative rates of capillary flow down two or more arms of a common element of porous media in some alternatives, converging in which at least one of the arms has been modified by the addition of flow-modifying agents which affect the flow rate in response to the concentration of the analyte; or by detecting changes in the rate of the capillary flow of the sample fluid along a path through an element of porous media, or through multiple elements of porous media.

Abstract: Hemoglobin in a sample solution is quickly and reliably denatured; at the same time, quick and accurate measurement of hemoglobin and a hemoglobin derivative is realized. In a method for measuring hemoglobin and a hemoglobin derivative, and a reagent composition, a measurement kit, an analysis device, and an analysis system used in the method, a sample solution containing a blood component is treated with a nonionic surfactant, an oxidizing agent, and a metal salt to denature hemoglobin in the sample solution to measure the hemoglobin, and thereafter the amount of a hemoglobin derivative in the sample is measured by an immunological method using an antibody specifically binding to a denatured site of the denatured hemoglobin derivative.

Abstract: An apparatus for introducing a specimen into a flow cytometer comprises: a syringe having a hollow barrel containing the specimen, a plunger partially within the barrel and a needle that extends into a volume of a nozzle of the flow cytometer; a one-way port in the nozzle forming a seal against the needle; a mounting platform coupled to both the syringe and to the flow cytometer; and a syringe pump coupled to the plunger, the syringe pump comprising a motor, a drive mechanism coupled to the motor; and a clamping mechanism coupled to the drive mechanism, wherein the motor operates the drive mechanism so as to cause the clamping mechanism to depress the plunger into the barrel.

Abstract: A device for identifying infection by the malaria parasite includes a microfluidic device having an inlet and an outlet and a diagnostic channel interposed between the inlet and the outlet. The diagnostic channel includes a contact surface and a sample pump configured to pump a RBC-containing sample into the inlet. The contact surface may be at least one of hydrophilic and roughened. Malaria infected RBCs (miRBCs) interact with the contact surface and become immobilized thereon whereas non-infected RBCs continue to flow downstream in the diagnostic channel.

Abstract: A fast and sensitive method and device for protein sequencing are disclosed. The method uses a combination of Edman degradation chemistry and mass spectrometry to sequence proteins and polypeptides. A peptide degradation reaction is performed on a polypeptide or protein ion reactant in the gas phase. The reaction yields a first ion product corresponding to a first amino acid residue of the polypeptide or protein reactant and a polypeptide or protein fragment ion. The mass-to-charge ratio for the first ion product, or the polypeptide or protein fragment ion, or both, is then determined. The first amino acid residue of the polypeptide or protein reactant is then identified from the mass-to-charge ratio so determined.

Abstract: A microfluidic switching device that includes an upstream microfluidic channel configured to contain a liquid having particles therein and a plurality of outlet channels coupled to the upstream microfluidic channel at a junction. A dead-end side channel or LCAT is oriented generally perpendicular to the upstream microfluidic channel and coupled to the upstream microfluidic channel at the junction, the dead-end side channel having a gas contained therein. The device includes a transducer configured to apply an external source of acoustic energy. Actuation of the transducer effectuates symmetrical oscillation of a gas/liquid boundary at the junction. Preferably, the junction comprises a bifurcation with two outlets. Further, the LCAT has a leading edge and a trailing edge and wherein the trailing edge of the LCAT is substantially aligned with the bifurcation.

Abstract: An apparatus and method for analyzing characteristics of particles in a fluid stream. The particles may be intermittently illuminated at an interrogation location with a pulsed laser. A time-varying signal produced in response to the illumination may be analyzed as a function of a timing signal in order to determine characteristics of the particles in the fluid stream.

Abstract: A hand-held test meter for use with an analytical test strip in the determination of an analyte in a bodily fluid sample includes a housing; a microcontroller block disposed in the housing; and a phase-shift-based hematocrit measurement block. The phase-shift-based hematocrit measurement block includes a signal generation sub-block, a low pass filter sub-block, an analytical test strip sample cell interface sub-block, a transimpedance amplifier sub-block, and a phase detector sub-block. In addition, the phase-shift-based hematocrit measurement block and microcontroller block are configured to measure the phase shift of a bodily fluid sample in a sample cell of an analytical test strip inserted in the hand-held test meter and the microcontroller block is configured to compute the hematocrit of the bodily fluid sample based on the measured phase shift.

Abstract: A device for measuring blood coagulation time is formed from a first substrate; a second substrate; a spacer layer disposed between the first and second substrates, said spacer layer having an opening formed therein defining a sample receiving chamber, a vented sink chamber, and an elongated reservoir forming a conduit for liquid movement between the sample receiving chamber and the sink chamber; a first electrode disposed on the first substrate, said first electrode being exposed in the reservoir portion through a first opening in the spacer layer; and a second electrode disposed on the second substrate, said second electrode being exposed in the reservoir portion through a second opening in the spacer layer. The device of the invention is used in combination with an apparatus that is connected to the first and second electrodes for measuring current flow between the first and second electrodes.

Abstract: An assembly for testing platelet aggregation including an electrode subassembly that is mounted in a cuvette subassembly for use with relatively small samples containing platelets.

Abstract: Cells of a cell suspension are labeled by providing a microfluidic chamber having superparamagnetic labeling particles that are concentrated exactly at one inner surface of the chamber and charging the cell suspension into the chamber.

Abstract: Disclosed is an automated method and apparatus for automatically setting a drop delay period by detecting calibration particles in a waste stream. The drop delay is incremented over a series of drop delays and the number of calibration particles in the waste stream is detected for each drop delay. The drop delay is selected which has the least number of calibration particles in the waste stream.

Abstract: A droplet interference system for sorting cells and a method for the same. The droplet interference system including a droplet generating system for producing a droplet which hits a fluid stream causing a selected segment of the fluid stream, and the cells contained therein, to be separated from the fluid stream.

Abstract: A measuring device for magnetic flow cytometry has a microfluidic channel disposed along an enriching route such that a magnetically marked cell sample flowing through the microfluidic channel is aligned to magnetic guide strips, enriched by the magnetic field of a magnet at the floor of the channel, and guided past a sensor. The sensor and the magnetic guide strips are integrated on a semiconductor chip.

Abstract: An analysis system is provided which comprises an integrated analysis device and a test strip magazine, for determining an analyte in a body fluid, wherein the analysis system comprises a first group comprising reusable components and a second group of components comprising a plurality of disposable articles. The second group includes non-electronic and electronic components, with critical interfaces configured between two or more such components, wherein non-electronic components can be disconnected from electronic components at a disconnection point. In one embodiment, critical interfaces are produced and tested during production of the analysis system.

Abstract: A measurement chip (100) is disclosed for use with a microfluidic resistance network (20) comprising a microfluidic sample preparation stage (34, 38), a sample outlet (42) and a waste outlet (44) both in fluidic communication with said preparation stage. The measurement chip comprises a sample channel (104) for receiving a sample from said sample outlet (42), the sample channel comprising measurement means (120, 130) and having a first fluidic resistance; and a waste channel (114) for receiving a waste stream from said waste outlet (44) and having a second fluidic resistance.

Abstract: The present invention is directed to a cartridge device for a measuring system for measuring viscoelastic characteristics of a sample liquid, in particular a blood sample, comprising a cartridge body having at least one measurement cavity formed therein and having at least one probe element arranged in said at least one measurement cavity for performing a test on said sample liquid; and a cover being attachable on said cartridge body; wherein said cover covers at least partially said at least one measurement cavity and forms a retaining element for retaining said probe element in a predetermined position within said at least one measurement cavity. The invention is directed to a measurement system and a method for measuring viscoelastic characteristics of a sample liquid.

Abstract: The present invention is directed to a cartridge device for a measuring system for measuring viscoelastic characteristics of a sample liquid, in particular a blood sample, comprising a cartridge body having at least one measurement cavity formed therein and having at least one probe element arranged in said at least one measurement cavity for performing a test on said sample liquid; and a cover being attachable on said cartridge body; wherein said cover covers at least partially said at least one measurement cavity and forms a retaining element for retaining said probe element in a predetermined position within said at least one measurement cavity. The invention is directed to a measurement system and a method for measuring viscoelastic characteristics of a sample liquid.

Abstract: The present invention is directed to a cartridge device for a measuring system for measuring viscoelastic characteristics of a sample liquid, in particular a blood sample, comprising a cartridge body having at least one measurement cavity formed therein and having at least one probe element arranged in said at least one measurement cavity for performing a test on said sample liquid; and a cover being attachable on said cartridge body; wherein said cover covers at least partially said at least one measurement cavity and forms a retaining element for retaining said probe element in a predetermined position within said at least one measurement cavity. The invention is directed to a measurement system and a method for measuring viscoelastic characteristics of a sample liquid.

Abstract: This invention provides microfabricated devices and methods for detecting, analyzing and sorting biological materials and particles. Droplets containing the particles are provided in an extrusion fluid, passed through a detection region, and then directed into a branch channel according to predetermined characteristics. For example, cells or viral particles contained in droplets of aqueous solvent are flowed past a detector in the nonpolar extrusion fluid decane, and routed into a selected branch channel for subsequent analysis or use.

Abstract: A cartridge device having a receiving portion for receiving a blood sample and a jack portion for receiving a plug; a stirring device for circulating the blood sample within the receiving portion; and an electrode holder having at least one incorporated electrode wire pair; wherein the electrode holder is attachable to the cell such that one end of the at least one electrode wire pair forms a sensor unit for measuring the electrical impedance between the two electrode wires of the at least one electrode wire pair within the blood sample and that the opposite end of the at least one electrode wire pair forms a plug portion being connectable directly to the plug for an electrical connection of the sensor unit to an analyzer.

Abstract: The invention features devices and methods for the deterministic separation of particles. Exemplary methods include the enrichment of a sample in a desired particle or the alteration of a desired particle in the device. The devices and methods are advantageously employed to enrich for rare cells, e.g., fetal cells, present in a sample, e.g., maternal blood and rare cell components, e.g., fetal cell nuclei. The invention further provides a method for preferentially lysing cells of interest in a sample, e.g., to extract clinical information from a cellular component, e.g., a nucleus, of the cells of interest. In general, the method employs differential lysis between the cells of interest and other cells (e.g., other nucleated cells) in the sample.

Abstract: Methods, systems, and computer readable media for using actuated surface-attached posts for assessing biofluid rheology are disclosed. According to one aspect, a method for testing properties of a biofluid specimen includes placing the specimen onto a micropost array having a plurality of microposts extending outwards from a substrate, wherein each micropost includes a proximal end attached to the substrate and a distal end opposite the proximal end, and generating an actuation force in proximity to the micropost array to actuate the microposts, thereby compelling at least some of the microposts to exhibit motion. The method further includes measuring the motion of at least one of the microposts in response to the actuation force and determining a property of the specimen based on the measured motion of the at least one micropost.

Abstract: A method for the enumeration of micronucleated erythrocyte populations while distinguishing platelet and platelet-associated aggregates involves the use of a first fluorescent labeled antibody having binding specificity for a surface marker for reticulocytes, a second fluorescent labeled antibody having binding specificity for a surface marker for platelets, and a nucleic acid staining dye that stains DNA (micronuclei) in erythrocyte populations. Because the fluorescent emission spectra of the first and second fluorescent labeled antibodies do not substantially overlap with one another or with the emission spectra of the nucleic acid staining dye, upon excitation of the labels and dye it is possible to detect the fluorescent emission and light scatter produced by the erythrocyte populations and platelets, and count the number of cells from one or more erythrocyte populations in said sample.

Abstract: The invention relates to a method for detecting a plurality of antigenic molecules carried by erythrocytes and/or a plurality of anti-erythrocyte antibodies, said antigenic molecules carried by the erythrocytes consisting of antigenic molecules carried not only by the erythrocytes, but also by at least one other cell population, other than the blood group antigen molecules, said method comprising bringing a sample into contact with distinguishable beads, on which are attached a) antibodies specific for said antigens, or b) erythrocytes or erythrocyte membrane fragment.

Abstract: The invention relates to a method for detecting a plurality of antigenic molecules carried by erythrocytes and/or a plurality of anti-erythrocyte antibodies of an individual, comprising bringing a sample into contact with distinguishable beads, on which are attached a) antibodies specific for said antigens, or b) erythrocytes, erythrocyte membrane fragments or blood group antigens.

Abstract: Hemoglobin in a sample solution is quickly and reliably denatured; at the same time, quick and accurate measurement of hemoglobin and a hemoglobin derivative is realized. In a method for measuring hemoglobin and a hemoglobin derivative, and a reagent composition, a measurement kit, an analysis device, and an analysis system used in the method, a sample solution containing a blood component is treated with a nonionic surfactant, an oxidizing agent, and a metal salt to denature hemoglobin in the sample solution to measure the hemoglobin, and thereafter the amount of a hemoglobin derivative in the sample is measured by an immunological method using an antibody specifically binding to a denatured site of the denatured hemoglobin derivative.

Abstract: The present invention generally provides methods and systems for performing in vivo flow cytometry by using blood vessels as flow chambers through which flowing cells can be monitored in a live subject in vivo without the need for withdrawing a blood sample. In some embodiments, one or more blood vessels are illuminated with radiation so as to cause a multi-photon excitation of an exogenous fluorophore that was previously introduced into the subject to label one or more cell types of interest. In some other embodiments, rather than utilizing an exogenous fluorophore, endogenous (intrinsic) cellular fluorescence can be employed for in vivo flow cytometry. The emission of fluorescence radiation from such fluorophores in response to the excitation can be detected and analyzed to obtain information regarding a cell type of interest.

Abstract: A sorting methodology in which bulk analysis of samples that have a low probability of containing a rare particle is performed first. Only those samples in which the bulk analysis has detected one or more rare particles are subjected to a flow cytometry process to isolate the rare particle(s). In one embodiment, a microwell plate provides for high throughput sorting in an enclosed environment. The microwell plate includes a plurality of wells and a microfluidic layer adapted for flow cytometry wherein particles from a given well are interrogated and sorted into other wells. The microfluidic layer advantageously includes fluid switches to permit bi-directional flow cytometry.

Abstract: Disclosed is a self-tuning flow cytometer that uses a mathematical model to perform sort decisions that is based upon the biological response of the particular types of cells that are being sorted. In one embodiment, statistical calculations of the likelihood of an event belonging to a certain population are used to make the sort decisions. Automated self-tuning processes are used to optimize the operating parameters of the flow cytometer to achieve a selected purity with higher yield at optimal sorting speeds. The fully automated processes minimize user input and allows the user to select a desired purity while maximizing yield.

Abstract: Methods and apparatus are described for sampling and diluting concentrated emulsions, which may be oil-in-water emulsions, water-in-oil emulsions, or other concentrated emulsions. One method embodiment of the invention comprises obtaining a sample of a concentrated emulsion comprising a dispersed phase and a continuous phase fluid; measuring droplet concentration of the dispersed phase in the sample; and for droplet concentration of the sample greater than about 1000 ppm, diluting the sample with substantially pure continuous phase fluid, forming a first diluted emulsion. Methods of the invention include those wherein the obtaining of a sample comprises opening a fluid connection to a flowing stream comprising the concentrated emulsion, wherein the obtaining and diluting steps occur in real time.

Abstract: The present invention provides a reagent kit for detecting lupus anticoagulant which includes a first clotting time-measuring reagent containing manganese salt and a second clotting time-measuring reagent which contains manganese salt at a concentration lower than that of the first clotting time-measuring reagent or does not contain manganese salt and a method of determining the presence or absence of lupus anticoagulant using the kit.

Abstract: Subpopulations of spore-like cells expressing specific cell surface and gene expression markers are provided. In one embodiment, the cells express at least one cell surface or gene expression marker selected from the group consisting of Oct4, nanog, Zfp296, cripto, Gdf3, UtF1, Ecat1, Esg1, Sox2, Pax6, nestin, SCA-1, CD29, CD34, CD90, B1 integrin, cKit, SP-C, CC10, SF1, DAX1, and SCG10. Also provided are methods for purifying a subpopulation of spore-like cells of interest from a population of spore-like cells, and methods for inducing differentiation of the isolated spore-like cells into cells of endodermal, mesodermal or ectodermal origin. The spore-like cells can be used to generate cells originating from all three germ layers and can be used to treat a patient who has a deficiency of functional cells in any of a wide variety of tissues, including the retina, intestine, bladder, kidney, liver, lung, nervous system, or endocrine system.

Abstract: A specimen analyzing method and a specimen analyzing apparatus capable of measuring interference substances before analyzing a specimen. The method comprises a step for sucking the specimen stored in a specimen container (150) and sampling it in a first container (153), a step for optically measuring the specimen in the first container, a step for sampling the specimen in a second container (154) and preparing a specimen for measurement by mixing the specimen with a reagent in the second container, and a step for analyzing the specimen for measurement according to the results of the optical measurement of the specimen.

Abstract: An optical material is inlaid into a supporting substrate, with the top surface of the optical material flush with the top surface of the substrate, wherein the optical element is used to shape a beam of light travelling substantially parallel to the top surface of the substrate, but with the central axis of the beam below the top surface of the substrate. The optical elements serve to shape the beam of light for delivery to or from a microfabricated structure within the device.

Abstract: The inventions relates to compositions and method for determining the absolute counts of cells per unit volume of a sample. Such a method comprises: (a) providing a container containing (i) a predetermined quantity of microparticles; and (ii) a cell-binding agent; in which the microparticles are disposed in or on a matrix which adheres to at least one wall of the container such that substantially all the microparticles are thereby attached to the container; (b) adding a known volume of sample to the container; (c) determining the ratio of microparticles to cells by counting microparticles and cells in a volume of the sample; and (d) determining the absolute count of cells by multiplying the number of cells per microparticle by the concentration of microparticles in the sample.

Abstract: A system and apparatus for sorting a mixture of stained particles in a fluid flow path, including stained particles. The system can include a pulsed electromagnetic radiation source for exciting fluorescence emissions from the stained particles, a photodetector for detecting the fluorescence emissions from the stained particles, a processor for classifying the stained particles; and a photo-damaging laser for damaging selected particles in the flow path.

Abstract: The present invention provides a blood analyzer and a blood analyzing method capable of obtaining information regarding B lymphocytes and T lymphocytes without using a fluorescence-labeled antibody. The blood analyzer of the present invention includes a blood specimen supplying portion, a sample preparation portion that prepares a measurement sample without using a fluorescence-labeled antibody by mixing a blood specimen supplied from the blood specimen supplying portion, a hemolyzing agent, and a fluorescent dye that stains nucleic acid, a light source, a first detector that detects fluorescence, a second detector that detects scattered light, and information processing portion that classifies lymphocytes based on the intensity of fluorescence and scattered light, and based on the fluorescence intensity of the classified lymphocytes, obtains information regarding B-lymphocytes and T-lymphocytes.

Abstract: The present invention provides a method for reducing undesirable light emission from a sample using at least one photon producing agent and at least one photon reducing agent (e.g. dye-based photon reducing agents). The present invention further provides a method for reducing undesirable light emission from a sample (e.g., a biochemical or cellular sample) with at least one photon producing agent and at least one collisional quencher. The present invention also provides a method for reducing undesirable light emission from a sample (e.g., a biochemical or cellular sample) with at least one photon producing agent and at least one quencher, such as an electronic quencher. The present invention also provides a system and method of screening test chemicals in fluorescent assays using photon reducing agents. The present invention also provides compositions, pharmaceutical compositions, and kits for practicing these methods.